Nearly two thirds of Bangladesh’s land area is less than five metres above sea level. The country’s terrain is flat and low-lying, situated in the Delta of three major rivers: the Ganges, Brahmaputra and Meghna. According to the Intergovernmental Panel on Climate Change (IPCC, 2014), 27 million people in Bangladesh will be at risk due to the rising sea level by 2050.
Bangladesh’s Ministry of Environment and Forests reckons that the sea-level rise (SLR) will amount to 14 centimetres by 2030, to 32 centimetres by 2050 and to 88 centimetres by 2100. The common perception is that land will be inundated, so people will be displaced. This danger is real, but it is probably overestimated as inundation of mass land area is unlikely (Nishat, 2017; Brammer, 2014). Migration to the cities from the coastal areas, especially Dhaka, the capital, is more likely to be driven by livelihood stress arising from salinisation (the situation is similar on the Indian side of the border – see comment by A.K. Ghosh).
Dwindling fresh water supply
The country’s fresh water supply will be affected as saline water is pushed upstream. The water logging potential will grow. Salinisation will thus affect arable land. It will also affect underground aquifers. Agriculture in coastal areas will suffer (Huq and Ayers, 2007).
Salinity is not only increasing because of SLR and tidal surges, however. Other issues matter too. For instance, the Farrakka barrage on the Ganges in India has reduced the inflow of fresh water. Land erosion, land-use change and the construction of embankments and dykes along coasts are adding to the problem.
Climate models, however, show that salinity levels will increase further as the sea level rises. Coastal communities will find it ever harder to get safe water.
The World Health Organization (WHO) recommends a daily dietary intake of 2.0 grammes of salt. As freshwater sources become scarce, people in the south-west coastal region are forced to drink saline water. A study (Khan et al, 2011) found that people’s daily salt consumption in the Khulna District already amounted to five to 16 grammes of salt from drinking water in the dry season. Such levels of salt consumption are linked to multiple health risks, including hypertension, kidney failure and diarrhoea. Pregnant women are at risk of pre-eclampsia, which may lead to severe headaches, organ damage and even death (Khan et al, 2014). A study commissioned by the World Bank (2015) showed that saltwater consumption during pregnancy is also linked to infant mortality.
Rising salinity, moreover, degrades agricultural land. Accordingly, fields that were historically used to cultivate rice and other crops have been converted into ponds for shrimp farming. This trend is particularly evident in Satkhira, one of the districts most affected by salinisation. In 1975, 80 % of the area was used for fields. In 2005, the share was only 15 %. In the same time span, the area used for shrimp cultivation increased from two percent to 72 %.
Such developments have serious social implications. Shrimp farming mostly benefits rich farmers, whereas poor farmers and marginalised communities suffer. One reason is that shrimp farming is not as labour intensive as rice farming, so landless labourers and sharecroppers lose out. Eventually, the men are forced to look for work in urban areas, while women are left behind with children and the elderly. In lack of male partners, women become more vulnerable, but their economic activity becomes more important. For obvious reasons, however, there are fewer opportunities to work in agriculture.
Data from 14 districts for the years 1994 to 2010 indicate that crop failures have a strong impact on migration (Gray and Mueller, 2012). Some coastal areas, where three rice harvests were feasible in the past, now only have one crop, mostly because of rising salinity.
Generally speaking, moreover, the poor depend more on ecosystem services which are degraded by climate change. For example, the livelihoods of poor communities who rely on the Sundarbans mangrove forest will suffer because of salinisation. Scholars assessed different aquatic salinity scenarios on behalf of the World Bank (2016). They predict that rising salinity will negatively affect 14 mangrove species, and in particular the valuable Sundari trees. The authors argue that “the greatest negative impacts” will be felt in the poorest sub-districts. The reasons are loss of timber value, reduced honey production and more incidents involving wildlife, including predators such as crocodiles and tigers.
For people’s food security, moreover, freshwater fish is very important. Unfortunately, relevant species are affected by salinisation, as research has shown (Gain et al, 2008). In Paikgacha, a highly saline sub-district of Khulna, fresh water species decreased by 59 % from 1975 to 2005. In Rampal, a moderately saline sub-district of Bagerhat, the comparative figure was 21 %. The slight increase in salt-tolerant species did not compensate for the loss. People’s protein supply has thus become more precarious, and biodiversity is dwindling.
Women at risk of disasters
Women and adolescent girls are at higher risk due to the impacts of global warming. They collect water for their families, and in the dry season, when freshwater sources become scarce, they have to walk farther. Sometimes they must hike up to ten kilometres every day. Because of sexual harassment, the journeys are not always safe. Moreover, women and adolescent girls in the area suffer gynaecological problems due to using saline water during menstruation (Islam et al, 2016).
The IPCC (2014) predicts that cyclones and tropical storms in general will become more intense. Bangladesh has actually improved disaster management dramatically. When Cyclone Bhola hit the Delta in 1970, some 300,000 to 500,000 people lost their lives. In 1991, a cyclone of comparable force claimed 135,000 lives. In 2007, Cyclone Sidr, which also had a speed of more than 250 kilometres, killed a mere 3,500 people. Bangladesh now has an early warning system and shelters, so people are much better prepared.
Nonetheless, cyclones cause huge damage. They seriously reduce peoples access to clean water because they destroy infrastructure and contaminate freshwater resources, worsening the salinity scenario.
When extreme weather events such as cyclones occur, women are more vulnerable than men. Historically, the female share of a cyclone’s death toll was 90 %. When Sidr struck in 2007, the share of female casualties was still more than 83 % (World Bank, 2013). One reason is that they have to fend not only for themselves, but also for children, the elderly, the sick and livestock. Evaluations have shown, moreover, that many women were not alerted in time by the early-warning system. On the upside, the absolute number of lives that Sidr claimed was at most about one percent of those claimed by Bhola in 1970.
Extreme weather events cause displacement, of course. The number of people concerned is likely to grow. Cyclone Sidr displaced nearly 650,000 people in 2007. Two years later, Cyclone Bijli, which belonged to a weaker category, displaced nearly 200,000 people. Such are often only temporary, however. The degradation of arable land has a more lasting impact.
In any case, it is estimated that an additional 2000 people move to the Dhaka agglomeration every day. The agglomeration is already one of the world’s most densely populated areas. Many migrants come from the coastal areas and hope to escape rural poverty. They mostly end up in slums and do informal work. Climate change is set to accelerate their race to the city.
Feisal Rahman is an assistant professor in the department of environmental science at Independent University, Bangladesh (IUB). He also coordinates the research programme of the International Centre of Climate Change and Development (ICCCAD). ICCCAD is a research centre based in Dhaka at IUB.
Brammer, H., 2014: Bangladesh’s dynamic coastal regions and sea-level rise. Climate Risk Management. Vol. 1, page 51-62.
Gain, A.K., et al, 2008: Impact of river salinity on fish diversity in the South-West coast region of Bangladesh.
Gray, C., and Mueller, V., 2012: Natural disasters and population mobility in Bangladesh.
Huq, S., and Ayers, J., 2007: Climate change impacts and responses in Bangladesh.
Islam, M.S., et al, 2016: Gender and water poverty.
IPCC, 2014: Assessment Report, Chapter on livelihoods and poverty.
Khan et al, 2011: Drinking water salinity and maternal health in coastal Bangladesh: implications of climate change.
Khan, A.E., et al, 2014: Salinity in drinking water and the risk of (pre)eclampsia and gestational hypertension in coastal Bangladesh.
Nishat, A., 2017: Projections of 17pc coastal inundation not factual.
World Bank, 2013: Improving women’s odds in disasters.
World Bank, 2015: Drinking water salinity and infant mortality in coastal Bangladesh.
World Bank, 2016: Impact of climate change and aquatic salinisation on mangrove species and poor communities in the Bangladesh Sundarbans.